The present invention relates to a vehicle driving apparatus. Conventional vehicle driving apparatuses so far known are described, for example, in Japanese Patent Application Laid-Open Nos. Hei 5-131858 and Hei 11-332019. Out of these two Publications, the former Publication discloses a hybrid vehicle in which front wheels are driven by the engine, and rear wheels are driven by an electric motor with a reduction gear, wherein at the start of the vehicle, a start acceleration according to the road surface condition is obtained, and the motor is controlled so as to able to obtain the start acceleration to enhance the start performance.
The latter Publication discloses a 4-wheel drive vehicle in which a prime mover is connected to a first driving shaft through an electric motor, and an electric motor is provided on a second driving shaft, wherein the electric motor for the first driving shaft is driven by the prime mover to generate electricity, and the electric motor for the second driving shaft is driven by power obtained by the generation, or generation is carried out by the electric motor for the second driving shaft, and the electric motor for the first driving shaft is driven by power obtained by the generation.
However, in the former using the electric motor with a reduction gear, since the constitution of the vehicle driving apparatus becomes complicated and becomes large in size, consideration is not taken into the improvement in mounting properties of the vehicle driving apparatus under the floor of the vehicle in a narrow space, and in the latter, since an inverter for driving and controlling the electric motor and an inverter for generating and controlling the electric motor are necessary, consideration is not taken into the enhancement of economization of the vehicle driving apparatus.
It is a main object of the present invention to provide a vehicle driving apparatus capable of being mounted easily even in a narrow space such as an area under the floor. It Is a further typical object of the present invention to provide a vehicle driving apparatus capable of constituting a 4-wheel drive vehicle using an electric motor without using expensive parts such as an inverter.
The fundamental characteristics of the present invention lies in that a first and a second generators driven by the internal combustion engine for driving one of front and rear wheel of a vehicle are installed in the vicinity of the internal combustion engine in a chamber in which the internal combustion engine is received, a so-called engine room, and an electric motor for driving the other of the front and rear wheels is arranged in the vicinity of a gear mechanism provided on the other axle of the front and rear wheels and with which a reduction mechanism is integrated. With this constitution, even in a narrow space such as a location under the floor of a vehicle, mounting of the vehicle driving apparatus is facilitated.
The gear mechanism is a differential gear located substantially in the central portion of the rear wheels. A first generator is provided to generate power for charging a battery as storage means or power for driving loads loaded on the vehicle, and is electrically connected to the charging power or the loads loaded. A second generator is provided to generate driving-power of an electric motor, and is electrically connected by a two-wire type wiring path.
The electric motor used may be either a DC motor or an AC motor. The second generator is of a closed type for circulating a cooling medium within the generator to cool it, and is arranged at a position below the first generator. The first generator is of an open type for taking open air as a cooling medium into the generator to cool it, and is arranged at a position above the second generator.
The vehicle driving apparatus is provided with control means for controlling the electric motor and the second generator. The control means is provided in a wiring path of the battery and the second generator and mounted in a vacant space in the engine room. Or, the control means is provided internally of an ABS control unit or an engine control unit.
The other fundamental characteristics lies in that an electric motor for driving a second axle of a vehicle comprises an induction motor having an armature winding of the same number of phases as that of an armature winding of a generator driven by a prime mover for driving a first axle of a vehicle, the armature winding of the generator and the armature winding of the induction motor are electrically connected, and a current flowing into a field winding of the generator is controlled to vary a voltage applied to the induction motor to control torque generated in the induction motor. With this constitution, there can be realized a 4-wheel drive vehicle using an electric motor without using expensive parts such as an inverter.
The vehicle driving apparatus is provided with a polarity switching device for switching the direction of a current flowing into the field winding of the generator. The induction motor can be rotated in any of normal and reverse directions by using the polarity switching device. The vehicle driving apparatus is provided with a rectifier for converting an AC output of an armature winding of a generator into a DC. A DC output of the rectifier can be used as a power supply of a field winding of a generator by using the polarity switching device.